Cylinder 2 and 4 misfire

JWAYNE8

MEMBER
2003 VOLKSWAGEN JETTA
1.8L
4 CYL
TURBO
2WD
AUTOMATIC

Took my car into the shop to get looked at because it was throwing the epc light! I would go to get into my car in the morning and it would start up fine and then I would stop to go into somewhere and come back out and it would be hard to start and the epc light would come on! Well they said it was the throttle body so they fixed that and now theres 2 cylinder misfires! So they changed the spark plugs and it helped it a lot but its still throwing the codes! They have also looked into anything that it could be and everything looks fine! What could this be?

1 Reply

BORIS K

MECHANIC
799 POSTS

Hello,

A cylinder misfire is usually caused by either faulty spark plugs, faulty ignition coils, an air leak or lack of cylinder compression.

In your case the replacement of the spark plugs seems to have improved but not cured your misfire. This points towards a possible ignition coil issue. It would be wise to first check if there is any engine oil leaking into the spark plug tubes. This can be caused by a possible faulty valve cover gasket.

It is easily checked by removing the coils and checking if these are wet with oil. If so, then the valve cover gasket needs changing.

How to check for misfire.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

How to check misfire on 1.8 20V engine.

https://youtu.be/1k9nFGaEHpk

How to do a compression test.

https://www.2carpros.com/articles/how-to-test-engine-compression

See picture below of an ignition coil for your vehicle.

Please let us know how you get along.

Cheers, Boris

Image (Click to make bigger)